Minimum input air providing device and method

ABSTRACT

An airflow proving device is provided. The device includes: a housing defining an airflow pathway; a first chamber within the housing; a second chamber within the housing located downstream in the flow pathway from the first chamber; structure in the housing defining an orifice, the orifice providing fluid communication between the first and second chamber and being part of the fluid pathway; and a pressure measuring device having a first sensor configured to monitor a pressure in the first chamber and a second sensor configured to monitor a pressure in the second chamber.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to an apparatus and method forconfirming airflow through a pathway. More particularly, the presentinvention relates to an apparatus and method for confirming airflowthrough a system that includes a combustion device.

BACKGROUND OF THE INVENTION

Combustion systems such as boilers, furnaces or any other commercial orhousehold combustion system rely on air flowing through the system toassure proper combustion at the burner. Good and reliable flow of airthrough the system aids to provide complete combustion of the fuel.Manufacturers of equipment which utilize combustion as an energy sourceare continuing to increase the turndown ratio of that equipment. Theturndown ratio is the ratio of the minimum and maximum input rate of aparticular unit. What may be input may be air, fuel, or a combination ofan air-fuel mixture.

As the minimum input rate decreases, the ability to accurately controlthe combustion process may become increasingly difficult. When certainconditions present themselves, for example, blocked combustion air,blocked exhaust pipes, or wind conditions at the vent termination unitmay cause the combustion process to lose stability or efficiency. Thisloss in combustion may create incomplete combustion which can createlarge amounts of carbon monoxide or even loss of flame. These and otherundesirable conditions may be the result of a lack of airflow throughthe combustion system. As a result, it can be difficult to ensure thatat least a minimal amount of air is, in fact, flowing through thecombustion system.

Relying on a setting for a blower to provide accurate informationregarding flow of air through the system may be problematic. Blowerswill tend to run and perhaps even increase in speed when there areblockages of airflow through the system. As a result, while the blowerspeed may provide a good approximation of airflow during idealconditions, blower speed does not always provide a reliable indicationof airflow during adverse conditions such as, for example, but notlimited to, blockages in the airflow path or wind conditions at the venttermination unit. As a result, reliance on the blower speed alone doesnot confirm an amount of air flowing through the system.

Accordingly, it is desirable to provide a method and apparatus that mayprovide a more reliable indication of air flowing through the system andspecifically, confirmation of a minimum of input air flowing through thesystem.

SUMMARY OF THE INVENTION

The foregoing needs are met, to a great extent, by the presentinvention, wherein in one aspect an apparatus is provided that in someembodiments a method and apparatus may provide a more reliableindication of air flowing through the system and specifically,confirmation of a minimum of input air flowing through the system.

In accordance with one embodiment of the present invention, an airflowproving device is provided. The device includes: a housing defining anairflow pathway; a first chamber within the housing; a second chamberwithin the housing located downstream in the flow pathway from the firstchamber; structure in the housing defining an orifice, the orificeproviding fluid communication between the first and second chamber andbeing part of the fluid pathway; and a pressure measuring device havinga first sensor configured to monitor a pressure in the first chamber anda second sensor configured to monitor a pressure in the second chamber.

In accordance with another embodiment of the present invention, a methodfor confirming airflow is provided. The method includes: configuring airto flow between a first chamber and a second chamber through an orifice;measuring an air pressure associated with the first chamber; measuringan air pressure associated with the second chamber; comparing the twomeasured pressures against a threshold; and adjusting a speed associatedwith the blower depending upon the difference between the air pressureassociated with the first chamber and the air pressure associated withthe second chamber falls below the threshold.

In accordance with yet another embodiment of the present invention, anairflow proving device is provided. The device may include: means fordefining an airflow pathway; a first chamber within the housing; asecond chamber within the housing located downstream in the flow pathwayfrom the first chamber; means for defining an orifice, the orificeproviding fluid communication between the first and second chamber andbeing part of the fluid pathway; and means for comparing measuringpressure having a first means for sensing a pressure in the firstchamber, and a second means for sensing pressure associated with thesecond chamber.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are, of course, additional embodimentsof the invention that will be described below and which will form thesubject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a combustion system incorporating aminimum input air proving device in accordance with the disclosure.

FIG. 2 is a schematic, cross-sectional view of a minimum input airproving device in accordance with the disclosure.

FIG. 3 is a flowchart outlining steps for accomplishing a method ofcontrolling a combustion system that includes confirming an amount ofair flowing through the system in accordance with the disclosure.

DETAILED DESCRIPTION

The invention will now be described with reference to the drawingfigures, in which like reference numerals refer to like partsthroughout. An embodiment in accordance with the present disclosureprovides a method and apparatus for determining or verifying that thereis at least a minimal airflow through the system.

A combustion system 10 is shown in FIG. 1. The combustion system 10includes a controller 12 operably connected to various components in thesystem 10. An airflow proving device 14 in accordance with thisdisclosure is mounted in an initial portion of an air pathway. The airflow proving device 14 includes a pressure measuring device 15. Theairflow proving device 14 has an air inlet 16 and an air outlet 18.Airflow is represented by arrows A through the system 10. Air flowsthrough the air inlet 16 through the airflow proving device 14 and outthe air outlet 18. The air pathway continues through the airflow provingdevice 14 through a conduit 20 into the inlet 22 of an air/fuel mixturedevice 24. In the air/fuel mixture device 24, fuel is combined with theair flowing through the airflow pathway. In some embodiments, the airand fuel mixing may occur via a venturi-type system. In otherembodiments other ways of mixing the air and fuel together may occur inaccordance with this disclosure.

After the air and fuel have mixed in the air/fuel mixture device 24, theair/fuel mixture will flow through the outlet 26 through the conduit 28into the inlet 30 of the blower 32. The blower 32 moves the air and/orair/fuel mixture through the system 10. The after the air/fuel mixtureflows to the blower 32 it flows out of the outlet 34 into the conduit 36and into the inlet 38 of the combustion device 42. Once the air/fuelmixture is in the combustion device 42, it will combust as controlled bythe combustion device 42. After combustion, the exhaust gases will flowout of the outlet 40 and through the exhaust system 41.

In some embodiments, the combustion device 42 may be a furnace, aboiler, heater, or any other combustion device. While the examples setforth herein primarily discuss combustion used in domestic or commercialheat this disclosure may also be applicable to any type of combustiondevice.

FIG. 2 is a close-up cutaway view of an air flow proving device inaccordance with an embodiment. The airflow proving device 14 includes awall 50 that defines an orifice 52. The orifice 52 provides fluidcommunication between the inlet chamber 54 and the outlet chamber 56.Air, as represented by arrow A, flows into the inlet 16 and into theinlet chamber 54. The air continues to flow through the orifice 52 intothe outlet chamber 56 out of the outlet 18 and into the conduit 20 andcontinues along the fluid pathway as illustrated and described withrespect to FIG. 1.

The pressure measuring device 15 has two leads 46 and 48. The lead 46 isconfigured to sense a pressure associated with the air in the inletchamber 54. The lead 48 is configured to sense an air pressureassociated with the outlet chamber 56. In embodiments where the pressuremeasuring device 15 is simply a pressure switch, if a difference betweenthe pressure sensed by leads 46 and 48 goes below a minimum threshold,then the pressure measuring device 15 will send a signal via connection44 to the controller 12. In this case, the pressure measuring device 15acts like a pressure switch and trips if a minimum threshold isexceeded.

In other embodiments, the pressure measuring device 15 acts as apressure sensor and sends signals to the controller 12 via theconnection 44 indicative of a difference in pressure detected by leads46 and 48.

In some embodiments, if the orifice 52 is sized appropriately withrespect to a desired airflow, as air flows through the airflow provingdevice 14 as represented by arrow A, the airflow will encounter abottleneck at orifice 52. This will cause pressure to decrease withinchamber 56 in comparison to chamber 54. If a lot of air is movingthrough the airflow proving device 14, then there will be a largepressure difference between chambers 54 and 56. This pressure differencewill be a result of a vacuum in chamber 56 as a result of the bottleneckof air trying to flow through the orifice 52. If no or little air isflowing through the airflow proving device 14 then the pressures betweenchambers 54 and 56, as sensed or detected by the pressure measuring thedevice 15, will approach or equal a zero difference in pressure. As aresult, the higher difference in pressure detected by leads 46 and 48will indicate higher airflow through the airflow proving device 14.Thus, the pressure measuring device 15 can confirm by measuringdifferent pressures within chambers 54 and 56, whether air is flowingthrough the air proving device 14.

Returning to FIG. 1, in some embodiments, the controller 12 is connectedvia connections 44 to the pressure measuring device 15, the air/fuelmixture device 24, the blower 32, and the combustion device 42. In otherembodiments, the controller 12 may be connected only to the pressuremeasuring device 15 and the blower 32. In other embodiments thecontroller 12 may be connected to the pressure measuring device 15, theblower 32, and any other combination of elements within the system 10.

In some embodiments, the signals received by the controller 12 from thepressure measuring device 15 will allow the controller 12 to determinewhether to speed up, slow down, maintain speed, or turn off the blower32. In other embodiments, feedback or signals received by the controller12 from the pressure measuring device 15 may result in the controller 12generating other control signals to other components of the system 10.For example, depending on signals received by the controller 12 from thepressure measuring device 15, the controller 12 may give control signalsto the air/fuel mixture device 24, the blower 32, the combustion device42, or any combination of those elements.

In some embodiments, the minimum threshold settings may be programmed bya user or set at the factory. These settings may remain fixed until thecontroller 12 is reprogrammed. In some embodiments, control settings orpresent conditions at various components such as the air/fuel mixturedevice 24, the blower 32, or the combustion device 42, may result in thecontroller reacting differently to signals received from the pressuremeasuring device 15. For example, if the blower 32 is set at arelatively slow speed causing air and/or air/fuel mixture to flowthrough the system 10 at a relatively slow pace, then the controller 12will allow the blower 32 to operate without further signals from thecontroller to change operation of the blower 32 when signals from thepressure measuring device 15 indicate a relatively low airflow in theairflow proving device 14. Thus, the threshold that the controller 12uses to make decisions on whether to interfere with operation of othercomponents within the system 10 may depend upon the current setting ofthose components. As a result, if, for example, the blower 32 isoperating at a relatively high speed, then the controller 12 will demanda relatively high amount of air flow through the airflow proving device14 as detected by the pressure monitoring device 15, but if the blower32 is operating at a relatively low speed, then the controller 12 willlower the threshold of detective air flowing through the air provingdevice 14 before interfering with operation blower 32 or any of theother components in the system 10. One of ordinary skill in the art,after reviewing this disclosure, will understand what thresholds toprogram into the controller to achieve desired system performance.

FIG. 3 illustrates an example method that may be accomplished by thesystem 10. For example in step S1, the system 10 measures pressure. Thiscan be accomplished by the pressure measuring device 15 sensing adifference in pressure within the chambers 54 and 56. In step S2, thecontroller 12 may send a control signal to the blower 32. This controlsignal may, in some embodiments, be to shut down the blower 32. In otherembodiments, this control signal may be to speed up or slow down theblower 32. In an optional step S3, depending upon the measured pressuredone at step S1, the controller 12 may send a control signal to othersystem components such as the combustion device 42 and/or the air/fuelmixture device 24.

In embodiments where the pressure measuring device 15 is a pressureswitch, if there is little or no difference (the difference falls belowa minimal threshold) the pressure switch 15 may send a signal to thecontroller 12 indicating such. The controller 12 will then detect thatthe airflow through the system 10 is below a minimum threshold and thenshut down the blower 32 and or combustion device 42. In someembodiments, the controller 12 may also shut down other components suchas the air/fuel mixture device 24. In some embodiments where thepressure measuring device 15 is a pressure switch 15 and the differencein pressure detected in chambers 54 and 56 falls below a minimumthreshold, the controller 12 may increase the speed of the blower 32 andwait a preset amount of time to see if there is a pressure increase inchamber 54 with respect to chamber 56. If the difference in pressurebetween chambers 54 and 56 still remain below the minimum thresholdafter the set amount of time, the controller 12 may then shut down any,all, or some of the other components in the system 10 such as, but notlimited to, the blower 32, the combustion device 42, and the air/fuelmixture device 24.

In embodiments where the pressure measuring device 15 is a pressuresensor, then the controller 12 may have different minimum thresholddifferences in pressure between the chambers 54 and 56 depending uponthe speed of the blower 32. If the detected difference in pressure fallsbelow a minimum threshold for a given speed, the controller 12 may shutdown one, all, or some of the components of the system such as, but notlimited to, the blower 32, the combustion device 42, or the air/fuelmixture device 24. In other embodiments, when the pressure differencebetween the chambers 54 and 56 fall below a minimum threshold for agiven blower speed, the controller 12 may increase the blower speed andawait a set amount of time and re-measure the difference in pressuresbetween the chambers 54 and 56. If the pressure differential is stillbelow minimum threshold, then the controller 12 may shut down any, all,or portions of the system such as, but not limited to, the blower 32,the combustion device 42, and/or the air/fuel mixture device 24.

In some embodiments, when the detected pressure differential between thechambers 54 and 56 falls below a minimum threshold, the controller 12may also set off an alarm indicator in addition to shutting down variouscomponents of the system 10.

After reviewing this disclosure, one of ordinary skill in the art willunderstand what minimum thresholds should be for a given system 10. Thesystem operator will also understand what time periods are appropriate,if any, for measuring the pressure differential between chambers 54 and56 after a first control signal has been sent. One of ordinary skill inthe art, after viewing this disclosure, will also understand what sizethe orifice 52 should be for a specific system 10. Other dimensions andsettings will also be understood.

Although an example of the system is shown and described, for home orcommercial heating systems, it will be appreciated that other combustionsystems can use features discussed herein.

The many features and advantages of the invention are apparent from thedetailed specification, and thus, it is intended by the appended claimsto cover all such features and advantages of the invention which fallwithin the true spirit and scope of the invention. Further, sincenumerous modifications and variations will readily occur to thoseskilled in the art, it is not desired to limit the invention to theexact construction and operation illustrated and described. Accordingly,all suitable modifications and equivalents may be resorted to, fallingwithin the scope of the invention.

What is claimed is:
 1. An airflow proving device comprising: a housingdefining an airflow pathway; a first chamber within the housing; asecond chamber within the housing located downstream in the flow pathwayfrom the first chamber; structure in the housing defining an orifice,the orifice providing fluid communication between the first and secondchamber and being part of the fluid pathway; and a pressure measuringdevice having a first sensor configured to monitor a pressure in thefirst chamber and a second sensor configured to monitor a pressure inthe second chamber.
 2. The airflow proving device of claim 1, whereinthe pressure measuring device is a pressure switch.
 3. The airflowproving device of claim 2, further comprising a controller operativelyconnected to the pressure measuring device and operatively connectedwith a blower fluidly connected to the airflow pathway.
 4. The airflowproving device of claim 3, wherein the controller is configured to turnoff the blower if the pressure switch is tripped.
 5. The airflow provingdevice of claim 1, further comprising a system to which the airflowproving device is part of the system further comprising: a controlleroperatively connected to the pressure measuring device; a fuel mixingdevice configured to add fuel to air in the airflow; a blower configuredto move the air and fuel along the airflow pathway; and a combustiondevice configured to receive the air/fuel mixture from the airflowpathway and burn the fuel in the air.
 6. The airflow proving device ofclaim 5, wherein the fuel mixing device is operatively connected to thecontroller and the controller is configured to adjust an air/fuelmixture in the airflow.
 7. The airflow proving device of claim 5,wherein the controller is operatively connected to the blower and isconfigured to turn on and off the blower.
 8. The airflow proving deviceof claim 5, wherein the controller is operatively connected to theblower and is configured to adjust a speed associated with the blower.9. The airflow proving device of claim 5, wherein the controller isoperatively connected to the combustion device and is configured tocontrol combustion occurring within the combustion device.
 10. Theairflow proving device of claim 1, wherein the pressure measuring deviceis a pressure transducer.
 11. The airflow proving device of claim 10,further comprising a controller operatively connected to the pressuremeasuring device and operatively connected with a blower fluidlyconnected to the airflow pathway and the controller is configured toadjust a speed associated with the blower.
 12. The airflow provingdevice of claim 1, further comprising a controller operatively connectedto the pressure measuring device and the blower wherein the controlleris configured to adjust the speed associated with the blower if adifference in pressure measured by the first sensor and second sensorfalls below a threshold.
 13. The airflow proving device of claim 12,wherein the controller will adjust the speed associated with the blowerto be faster if a difference in pressure measured by the first sensorand the second sensor falls below a first threshold.
 14. The air provingdevice of claim 13, further comprising additional thresholds after thefirst threshold, wherein the controller is configured to increase aspeed associated with the blower after the difference in pressuremeasured by the first sensor and second sensor falls below each of thethresholds.
 15. The air proving device of claim 14, further comprising afinal threshold and the controller is configured to shut down the blowerif the pressure measured by the first and second sensors falls below thefinal threshold.
 16. The air proving device of claim 12, wherein thecontroller will turn off the blower if a difference in pressure measuredby the first sensor and second sensor falls below the threshold.
 17. Theairflow proving device of claim 12, wherein the controller includes atiming device and the controller is further configured to increase aspeed associated with the blower when the difference in pressuremeasured between the first sensor and the second sensor falls below athreshold and if the difference in pressure measured between the firstsensor and the second sensor does not increase past a second thresholdafter a set amount of time after the speed associated with the blowerhas increased, then the controller will turn off the blower.
 18. Theairflow proving device of claim 12, wherein the threshold is differentdepending upon the current speed associated with the blower.
 19. Amethod for confirming airflow comprising: configuring air to flowbetween a first chamber and a second chamber through an orifice;measuring an air pressure associated with the first chamber; measuringan air pressure associated with the second chamber; comparing the twomeasured pressures against a threshold; and adjusting a speed associatedwith the blower depending upon the difference between the air pressureassociated with the first chamber and the air pressure associated withthe second chamber falls below the threshold.
 20. An airflow provingdevice comprising: means for defining an airflow pathway; a firstchamber within the housing; a second chamber within the housing locateddownstream in the flow pathway from the first chamber; means fordefining an orifice, the orifice providing fluid communication betweenthe first and second chamber and being part of the fluid pathway; andmeans for comparing measuring pressure having a first means for sensinga pressure in the first chamber, and a second means for sensing pressureassociated with the second chamber.